A Microbial Fuel Cell (MFC) is a device in which a microbial population present in a liquid or semi-liquid microbial medium performs electrochemical reactions to provide an electrical current through an external circuit disposed between an anode and a cathode. A typical MFC 100 is shown in FIG. 1 by way of an example. The MFC 100 includes a vessel 110 divided into an anode chamber 120 and a cathode chamber 130 by a semi-permeable membrane 140, which is typically a proton exchange membrane (PEM). The semi-permeable membrane 140 provides a conduction path for hydrogen ions but not electrons, which then must travel over the external circuit 180 to reach the cathode 160.
An anode 150 is provided in the anode chamber 120 while a cathode 160 is provided in the cathode chamber 130. Further, a population of microbes 170 is provided in the anode chamber. An external circuit electrically connects the anode 150 and the cathode 160. Each of the chambers 120, 130, is provided with a solution 190 in which the anode 150 and cathode 160 are at least partially immersed and within which the population of microbes 170 is maintained.
In operation, a nutrient is added to the solution 190 and the microbes 170 consume the nutrient, under anaerobic conditions in the anode chamber. The microbes 170 therefore obtain oxygen by splitting water into hydrogen ions, oxygen, and electrons. The oxygen is combined with the carbon from the nutrient to form carbon dioxide, the hydrogen ions migrate across the membrane 140 to the cathode 160, and the electrons traverse the external circuit 180 from the anode 150 to the cathode 160 where the electrons combine with the hydrogen ions.